The best approach if you come across an item on a form that does not pertain to your situation is to either write "N/A" (not applicable) in the space provided or leave the space blank. Writing an explanation in the margin of the application may not be necessary, as long as it is clear that the item is not relevant to your circumstances. Cross out the item and writing one that pertains to you is not recommended, as it may lead to confusion or misinterpretation.
